Chair

ABSTRACT

A chair includes a backrest and a seat surface. The backrest is adjustable relative to the seat surface, and the backrest is adjustable in its inclination independently of the position of the seat surface. The adjustment of the inclination of the backrest occurs in a stepless manner and without an operating mechanism.

The invention concerns a chair with a backrest which can be adjusted relative to a seat surface, and the backrest can be adjusted in its inclination independently of the position of the chair.

Chairs are known that are adjustable between a sitting and a reclining position. These are also known as sitting and reclining furniture. They allow an adjustment of the position between a “normal” upright sitting position and a somewhat horizontally oriented reclining position. An adjusted inclination of the backrest is maintained or the inclination of the backrest can be adjusted separately and independently of the position of the chair.

In one such chair, known from DE 296 00 282 U1, it is possible to perform the adjustment by moving the seat surface without major force, since a parallel linkage system is provided, which moves the body weight or the center of gravity backward along with the seat surface when the seat surface is shifted. The inclination of the backrest is adjusted by a gas pressure spring, which is controlled via a valve, which is activated via an operating lever.

A similar chair is known from the firm Steltemeier GmbH, Lippstadt. In this chair as well, an adjustment of the inclination of the backrest takes place via a gas pressure spring, controlled by means of operating lever and valve.

Such chairs have the drawback that the mechanism associated with the operating lever is complicated and prone to breakdown. Furthermore, the user must operate the lever to adjust the inclination, which is especially difficult in the reclining position. Moreover, the operating of the lever is not always intuitive, depending on its design, and so the user must have this explained to him or her.

The underlying problem of the invention is to create a chair in which the inclination of the backrest is possible in especially easy manner and in which furthermore the mechanism for the adjustment of the backrest is simple and robust in design, as well as intuitive in operation.

This problem is solved by the chair indicated in claim 1.

Because the chair is designed so that the adjustment of the inclination of the backrest occurs stepless without operating means, the operation is simple and intuitive. Moreover, the construction of the chair is simplified and thus it is robust, as well as economical, in its manufacture.

By operating means is meant, first of all, levers, screws, buttons, wheels, knobs, handles and the like, to be operated by the user, which when activated allow a changing of the inclination of the backrest, for which they activate, for example, valves of gas pressure springs, or release locking mechanisms or detent means. In addition, by operating means is meant mechanical solutions which enable an adjustment of the inclination of the backrest only after a releasing of a detent device by pressure against the backrest. One example of such a device is the use of a detent roller, which in the upright position of the backrest is held in a recess and needs to be forced out with a certain amount of force in order to make possible the movement of the backrest.

In the solution of the invention, neither an operating lever nor a locking or detent means is required. This, in fact, is what distinguishes the solution of the invention.

It is especially advantageous for the adjustment of the inclination to be configured such that the backrest can additionally be supported in any desired position. For then it is possible to hold or adjust the backrest in various positions not only stepless, but also with no particular activation or locking or detent means. Thus, the backrest can be tilted into any desired position and supported there, when the user leans back.

In a most especially preferred embodiment of the invention, a gas pressure spring is provided for adjusting the inclination of the backrest, which is provided with an elevated initial push-on force regardless of its respective position. Such a gas pressure spring is thus characterized in that a certain initial force has to be overcome to move the piston of the gas pressure spring, after which the further adjustment can occur with a smaller force. Such a gas pressure spring thus serves for force assistance and stepless positioning of the backrest and, on the other hand, ensures that the backrest is supported in every position with the user leaning back on it.

Preferably, the gas pressure spring is a friction gas spring or a gas pressure spring with pressure valve at the back side of the piston. Friction gas springs are characterized in that the piston is provided with an extra element with friction which must be overcome in order to move it. Such elements can be foam materials, which lie against the wall of the tube under a prestressing force and thus generate the needed extra friction. In addition, gas pressure springs are suitable in which the piston is outfitted with a pressure valve arranged on the back side of the piston, and the valve hinders the exchange or the pushing in of the piston rod until a spring-loaded gasket frees up the piston bore.

Such gas pressure springs are available, for example, from the firms STABILUS GmbH, Koblenz, Germany, or SUSPA GmbH, Altdorf, Germany.

Thus, in order to achieve an adjustment of the inclination of the backrest, the user only needs to lean back and overcome the initial force of the gas pressure spring by an additional pressing, e.g., against the arm rests. Then the user leans back as much as desired and only needs to halt the movement of the backrest in order to fix its position. If the user wishes to further increase the inclination, he can lean back again, overcoming the initial force, in order to achieve a further adjustment of the backrest.

According to another preferred embodiment of the invention, the gas pressure spring has a smaller push-out force than the push-on force. If the user would like to sit upright once again, that is, reduce the inclination of the backrest or make the backrest more upright, the user only need lean forward. Despite the reduced push-out force, it is large enough to restore the backrest to its position.

Advisedly, the spring characteristic is chosen so that the forces are adequate for persons of normal weight, i.e., they must apply a slight additional support pressure to accomplish the respective adjustment.

Additional features, properties and advantages of the present invention will emerge from the following description of the drawing. This shows:

FIG. 1, a perspective view of a chair according to the invention, without upholstery, the backrest being erect;

FIG. 2, a perspective view of the chair from FIG. 1, with backrest inclined, and

FIG. 3, a schematic diagram of the spring characteristic of a gas pressure spring, used according to the invention, with increased initial push-on force and reduced push-out force.

FIGS. 1 and 2 show a view of a chair according to the invention, designated overall as 1, from slanting left top perspective, in the sitting position without upholstery, i.e., for better comprehension, only the basic frame of the chair 1 and its mechanism are depicted. In FIG. 1, the chair 1 is shown with upright backrest, whereas the backrest in FIG. 2 is tilted back.

The chair 1 basically comprises a seat surface 2, a backrest 3, a swiveling leg rest 4 and a base 5.

The seat surface 2 can be shifted via a suitable link system between a sitting and reclining position, while the leg rest 4 is extended from its folded position and swiveled back again. This does not affect the inclination of the backrest 3.

The backrest 3 comprises a head piece 6 and a back piece 7, each of them formed from a tube frame and being joined together via side locking linkages 8, and between the sides of the pieces there are provided cross braces 9, in order to form a support surface for the lining or upholstery. Moreover, the chair 1 has a lower region 10, adjoining the back piece 7 at the bottom, forming a slight angle with the back piece 7. In the erect sitting position shown, the lower region 10 is somewhat vertical and the back piece 7 on the other hand is tilted backward by around 15 degrees from the vertical.

The backrest 3 is connected via the lower region 10 to the seat surface 2 and its mechanism, while on either side a corresponding bracket 11 and 12 is welded to the lower region 10 at the top and bottom, respectively. The brackets 11 are arranged on the outside at the transition between the back piece 7 and the region 10 and the brackets 12 are arranged with a slight distance from each other roughly in the center on the lower cross brace of the backrest 3.

The upper brackets 11 are each articulated to a lever 14, which in turn is articulated to another lever 16, which is rigidly joined by a round rod 17 to its counterpart on the other side. On the round rod 17 are welded, in turn, two brackets, which serve for the articulation to the rest of the chair 1 or parts of its base 5. The lever 14 arranged between the respective bracket 11 and the lever 16 has a roughly semicircular recess 18, which serves for the movable accommodation of the rear corner of the seat surface 2.

The lower brackets 12 are articulated to a gas pressure spring 13, which in turn is linked to a longitudinal brace 15 of the seat surface 2, arranged roughly in the middle between the front brace and the rear brace of the seat surface and being bent downwards in the edge region. Thus, the gas pressure spring 13 is connected, on the one hand, to the braces 12 and, on the other hand, to the longitudinal brace 15 via brackets 19.

The gas pressure spring 13 serves to adjust the inclination of the backrest 3, which can be adjusted independently of the seat surface 2.

The gas pressure spring 13 is a special gas pressure spring that is provided with an increased initial push-on force F1 regardless of its particular position (see FIG. 3).

Both so-called friction gas springs and gas pressure springs with pressure valve at the rear side of the piston can be used, such as are known by the names Hydro-Lift® from the Stabilus company.

Thus, to accomplish an adjustment of the inclination of the backrest 3, the user need only lean back and overcome the initial push-on force F1 of the gas pressure spring by an additional back push. After this, only the reduced push-on force F2 is still active and needs to be overcome, so that the user now need only lean back as much as desired to take up the desired position of the backrest 3.

At this point, the user simply lessens the pressure, so that the backrest 3 remains standing at the adjusted position and is held there against the weight of the person, thanks to the increased initial push-on force F1 still exerted from standstill. Thus, the user can also lean against the backrest 3 in any given position of the backrest 3.

If the user wishes a further adjustment of the inclination, he can once again lean backward, overcoming the initial push-on force F1, and thereby accomplish the adjustment of the backrest 3.

In addition, the gas pressure spring 13 has a smaller push-out force F3 than the push-on force F2. This is because the push-out force F3 corresponds roughly to the push-on force F2 minus the friction.

If the user would like to sit up again, that is, reduce the inclination of the backrest, or position the backrest 3 more steeply, the user need only lean forward. Thus, the push-out force F3 is chosen such that the backrest 3, while not “sliding” the user out from the chair 1, nevertheless restores itself.

The push-on forces F1 and F2, as with springs in general, increase slightly along the adjustment path. Accordingly, the push-out force F3 also decreases slightly along the adjustment path.

Advisedly, the spring characteristic (FIG. 3) of the gas pressure spring 13 is chosen so that the forces F1, F2 and F3 are appropriate for persons of normal weight, i.e., these persons must exert a slight additional pressure by pushing off to tilt the backrest backward. Of course, the gas pressure spring can also be selected so that the chair 1 is suitable for heavier persons.

The chair 1 is thus configured so that the adjustment of the inclination of the backrest 3 occurs stepless without operating means. In addition, the adjustment of the inclination is configured such that the backrest 3 can be held in any given position. The adjustment of the inclination of the backrest 3 functions entirely without operating means such as levers and the like, and without locking or detent means. Therefore, the operation is especially simple, because no special operation is required. Thus, the adjustment is intuitive and requires no explanation. Furthermore, the construction of the chair 1 is simplified, which leads to a cost savings during the manufacture and furthermore makes it more robust and maintenance friendly.

LIST OF REFERENCE SYMBOLS

-   1 chair -   2 seat surface -   3 backrest -   4 leg rest -   5 base -   6 head piece -   7 back piece -   8 linkage -   9 cross brace -   10 lower region of back piece -   11 bracket -   12 bracket -   13 gas pressure spring -   14 lever -   15 longitudinal brace -   16 lever -   17 round rod -   18 recess -   19 brackets 

1. A chair comprising: a backrest and a seat surface; said backrest being adjustable and relative to said seat surface, said backrest being adjustable in its inclination independently of the position of said seat surface; wherein the adjustment of the inclination of said backrest occurs in a stepless manner and without an operating mechanism.
 2. The chair as claimed in claim 1, wherein said backrest is adapted to be supportable in any desired position relative to said seat surface.
 3. The hair as claimed in claim 2, further comprising a gas pressure spring adapted to adjust the inclination of said backrest, said gas pressure spring having an elevated initial push-on force regardless of its respective position relative to said seat surface.
 4. The chair as claimed in claim 3, wherein said gas pressure spring comprises a friction gas spring or a gas pressure spring having a pressure valve at the back side of the piston.
 5. The chair as claimed in claim 4, wherein said gas pressure spring has a smaller push-out force than a push-on force.
 6. The chair as claimed in claim 5, wherein one end portion of said gas pressure spring is connected to said backrest and an opposite end of said gas pressure spring is connected to said seat surface.
 7. The chair as claimed in claim 6, wherein said gas pressure spring is connected to said seat surface with a longitudinal brace.
 8. The chair as claimed in claim 1, further comprising a gas pressure spring adapted to adjust the inclination of said backrest, said gas pressure spring having an elevated initial push-on force regardless of its respective position relative to said seat surface.
 9. The chair as claimed in claim 8, wherein said gas pressure spring comprises a friction gas spring or a gas pressure spring having a pressure valve at the back side of the piston.
 10. The chair as claimed in claim 8, wherein said gas pressure spring has a smaller push-out force than a push-on force.
 11. The chair as claimed in claim 8, wherein one end portion of said gas pressure spring is connected to said backrest and an opposite end of said gas pressure spring is connected to said seat surface.
 12. The chair as claimed in claim 8, wherein said gas pressure spring is connected to said seat surface with a longitudinal brace.
 13. A chair comprising: a backrest; a seat surface, said backrest being adjustable relative to said seat surface, and said backrest having an adjustable inclination independent of the position of said chair, wherein the adjustment of said inclination of said backrest occurs in a stepless manner and without operating mechanisms; and a gas pressure spring connected to said backrest, said gas pressure spring being adapted to adjust said inclination of said backrest.
 14. The chair as claimed in claim 13, wherein said gas pressure spring comprises a friction gas spring or a gas pressure spring having a pressure valve at the back side of the piston.
 15. The chair as claimed in claim 14, wherein said gas pressure spring has a smaller push-out force than a push-on force.
 16. The chair as claimed in claim 15, wherein one end portion of said gas pressure spring is connected to said backrest and an opposite end of said gas pressure spring is connected to said seat surface.
 17. The chair as claimed in claim 16, wherein said gas pressure spring is connected to said seat surface with a longitudinal brace.
 18. The chair as claimed in claim 13, wherein said gas pressure spring has a smaller push-out force than a push-on force.
 19. The chair as claimed in claim 13, wherein one end portion of said gas pressure spring is connected to said backrest and an opposite end of said gas pressure spring is connected to said seat surface.
 20. The chair as claimed in claim 19, wherein said gas pressure spring is connected to said seat surface with a longitudinal brace. 